SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a30ad1ba154c9f676250aafbef97d28382e8180d40175f316c15112aeb059f' 
  AND token = 'QOxb+UpSUBiSXXkMi4w7l4YbdbNQyFqOVaQXrf5kQQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}